Provided by: libzmq-dev_2.0.6beta.dfsg-2_i386 bug

NAME

       zmq_setsockopt - set 0MQ socket options

SYNOPSIS

       int zmq_setsockopt (void *socket, int option_name, const void
       *option_value, size_t option_len);

DESCRIPTION

       The zmq_setsockopt() function shall set the option specified by the
       option_name argument to the value pointed to by the option_value
       argument for the 0MQ socket pointed to by the socket argument. The
       option_len argument is the size of the option value in bytes.

       The following options are defined:

   ZMQ_HWM: Set high water mark
       The ZMQ_HWM option shall set the high water mark for the message queue
       associated with the socket. The high water mark is a hard limit on the
       number of outstanding messages in the queue; if this limit has been
       reached the socket shall enter an "emergency" state and depending on
       the socket type, 0MQ shall take appropriate action such as blocking or
       dropping new messages entering the queue.

       The default ZMQ_HWM value of zero means "no limit".

       Option value type
           int64_t

       Option value unit
           messages

       Default value
           0

       Applicable socket types
           all

   ZMQ_LWM: Set low water mark
       The ZMQ_LWM option shall set the low water mark for the message queue
       associated with the socket. This option only makes sense when used in
       conjunction with the ZMQ_HWM option. A socket which has reached it’s
       high water mark remains in the "emergency" state until the number of
       outstanding messages in it’s associated message queue falls below the
       low water mark, at which point normal message processing is resumed.

       Option value type
           int64_t

       Option value unit
           messages

       Default value
           0

       Applicable socket types
           all

   ZMQ_SWAP: Set disk offload size
       The ZMQ_SWAP option shall set the disk offload (swap) size for the
       message queue associated with the socket. A socket which has ZMQ_SWAP
       set to a non-zero value may exceed it’s high water mark; in this case
       outstanding messages shall be offloaded to storage on disk rather than
       held in memory.

       The value of ZMQ_SWAP defines the maximum size of the swap space in
       bytes.

       Option value type
           int64_t

       Option value unit
           bytes

       Default value
           0

       Applicable socket types
           all

   ZMQ_AFFINITY: Set I/O thread affinity
       The ZMQ_AFFINITY option shall set the I/O thread affinity for
       connections created by subsequent zmq_connect() or zmq_bind() calls on
       the specified socket.

       sockets. Affinity determines which threads from the 0MQ I/O thread pool
       associated with the socket’s context shall handle newly created
       connections. A value of zero specifies no affinity, meaning that work
       shall be distributed fairly among all 0MQ I/O threads in the thread
       pool. For non-zero values, the lowest bit corresponds to thread 1,
       second lowest bit to thread 2 and so on. For example, a value of 3
       specifies that subsequent connections on socket shall be handled
       exclusively by I/O threads 1 and 2.

       See also zmq_init(3) for details on allocating the number of I/O
       threads for a specific context.

       Option value type
           int64_t

       Option value unit
           N/A (bitmap)

       Default value
           0

       Applicable socket types
           N/A

   ZMQ_IDENTITY: Set socket identity
       The ZMQ_IDENTITY option shall set the identity of the socket. Socket
       identity determines if existing 0MQ infastructure (message queues,
       forwarding devices) shall be identified with a specific application and
       persist across multiple runs of the application.

       If the socket has no identity, each run of an application is completely
       separate from other runs. However, with identity set the socket shall
       re-use any existing 0MQ infrastructure configured by the previous
       run(s). Thus the application may receive messages that were sent in the
       meantime, message queue limits shall be shared with previous run(s) and
       so on.

       Identity should be at least one byte and at most 255 bytes long.
       Identities starting with binary zero are reserved for use by 0MQ
       infrastructure.

       Option value type
           binary data

       Option value unit
           N/A

       Default value
           NULL

       Applicable socket types
           all

   ZMQ_SUBSCRIBE: Establish message filter
       The ZMQ_SUBSCRIBE option shall establish a new message filter on a
       ZMQ_SUB socket. Newly created ZMQ_SUB sockets shall filter out all
       incoming messages, therefore you should call this option to establish
       an initial message filter.

       An empty option_value of length zero shall subscribe to all incoming
       messages. A non-empty option_value shall subscribe to all messages
       beginning with the specified prefix. Mutiple filters may be attached to
       a single ZMQ_SUB socket, in which case a message shall be accepted if
       it matches at least one filter.

       Option value type
           binary data

       Option value unit
           N/A

       Default value
           N/A

       Applicable socket types
           ZMQ_SUB

   ZMQ_UNSUBSCRIBE: Remove message filter
       The ZMQ_UNSUBSCRIBE option shall remove an existing message filter on a
       ZMQ_SUB socket. The filter specified must match an existing filter
       previously established with the ZMQ_SUBSCRIBE option. If the socket has
       several instances of the same filter attached the ZMQ_UNSUBSCRIBE
       option shall remove only one instance, leaving the rest in place and
       functional.

       Option value type
           binary data

       Option value unit
           N/A

       Default value
           N/A

       Applicable socket types
           ZMQ_SUB

   ZMQ_RATE: Set multicast data rate
       The ZMQ_RATE option shall set the maximum send or receive data rate for
       multicast transports such as zmq_pgm(7) using the specified socket.

       Option value type
           uint64_t

       Option value unit
           kilobits per second

       Default value
           100

       Applicable socket types
           all, when using multicast transports

   ZMQ_RECOVERY_IVL: Set multicast recovery interval
       The ZMQ_RECOVERY_IVL option shall set the recovery interval for
       multicast transports such as zmq_pgm(7) using the specified socket. The
       recovery interval determines the maximum time in seconds that a
       receiver can be absent from a multicast group before unrecoverable data
       loss will occur.

           Caution
           Excersize care when setting large recovery intervals as the data
           needed for recovery will be held in memory. For example, a 1 minute
           recovery interval at a data rate of 1Gbps requires a 7GB in-memory
           buffer.

       Option value type
           uint64_t

       Option value unit
           seconds

       Default value
           10

       Applicable socket types
           all, when using multicast transports

   ZMQ_MCAST_LOOP: Control multicast loopback
       The ZMQ_MCAST_LOOP option shall control whether data sent via multicast
       transports can also be received by the sending host via loopback. A
       value of zero disables the loopback functionality, while the default
       value of 1 enables the loopback functionality. Leaving multicast
       loopback enabled when it is not required can have a negative impact on
       performance. Where possible, disable ZMQ_MCAST_LOOP in production
       environments.

       Option value type
           uint64_t

       Option value unit
           boolean

       Default value
           1

       Applicable socket types
           all, when using multicast transports

   ZMQ_SNDBUF: Set kernel transmit buffer size
       The ZMQ_SNDBUF option shall set the underlying kernel transmit buffer
       size for the socket to the specified size in bytes. A value of zero
       means leave the OS default unchanged. For details please refer to your
       operating system documentation for the SO_SNDBUF socket option.

       Option value type
           uint64_t

       Option value unit
           bytes

       Default value
           0

       Applicable socket types
           all

   ZMQ_RCVBUF: Set kernel receive buffer size
       The ZMQ_RCVBUF option shall set the underlying kernel receive buffer
       size for the socket to the specified size in bytes. A value of zero
       means leave the OS default unchanged. For details refer to your
       operating system documentation for the SO_RCVBUF socket option.

       Option value type
           uint64_t

       Option value unit
           bytes

       Default value
           0

       Applicable socket types
           all

RETURN VALUE

       The zmq_setsockopt() function shall return zero if successful.
       Otherwise it shall return -1 and set errno to one of the values defined
       below.

ERRORS

       EINVAL
           The requested option option_name is unknown, or the requested
           option_len or option_value is invalid.

EXAMPLE

       Example 1. Subscribing to messages on a ZMQ_SUB socket

           /* Subscribe to all messages */
           rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "", 0);
           assert (rc == 0);
           /* Subscribe to messages prefixed with "ANIMALS.CATS" */
           rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "ANIMALS.CATS", 12);

       Example 2. Setting I/O thread affinity

           /* Incoming connections on TCP port 5555 shall be handled by I/O thread 1 */
           rc = zmq_setsockopt (socket, ZMQ_AFFINITY, 1, sizeof (int64_t));
           assert (rc);
           rc = zmq_bind (socket, "tcp://lo:5555");
           assert (rc);
           /* Incoming connections on TCP port 5556 shall be handled by I/O thread 2 */
           rc = zmq_setsockopt (socket, ZMQ_AFFINITY, 2, sizeof (int64_t));
           assert (rc);
           rc = zmq_bind (socket, "tcp://lo:5555");
           assert (rc);

SEE ALSO

       zmq_socket(3) zmq(7)

AUTHORS

       The 0MQ documentation was written by Martin Sustrik
       <sustrik@250bpm.com[1]> and Martin Lucina <mato@kotelna.sk[2]>.

NOTES

        1. sustrik@250bpm.com
           mailto:sustrik@250bpm.com

        2. mato@kotelna.sk
           mailto:mato@kotelna.sk